1. Technical Field
The present invention relates to methods and apparatus for performing evaporation/concentration of sample solutions and, more particularly, to automatic methods and apparatus for effecting evaporation/concentration, combined with solvent exchange, for a variety of different types of samples in sequence without operator intervention.
2. Discussion of the Prior Art
The primary utilization of evaporators is in the field of residue testing (i.e., testing the remaining constituents of a solution after evaporation of liquid therefrom (in a laboratory). The use of evaporation as part of a concentration and solvent exchange procedure is also important in laboratory practice. Prior art commercially available equipment for performing these functions requires manual operation and constant operator intervention. This has a serious impact on labor costs involved in sample preparation and subverts personnel from more productive laboratory work. Moreover, by involving the human factor in the process, accuracy and reproducibility of results are compromised.
Although it may be feasible to rearrange existing evaporators such that they can automatically receive and evaporate a single sample, such evaporators are not capable of sequentially receiving and evaporating samples of different solutions sequentially as part of an automated process. When a sample concentration and/or solvent exchange capability is also required, prior art evaporators are not suitable for automatic multiple sample preparation.
In evaporating sample solutions as part of an automatic procedure, it is important that the evaporation-producing energy which is applied to the solution be accurately controllable in order to permit the amount of liquid evaporated over a given time interval to be determinable. Accurate control of such applied energy cannot be achieved in prior art evaporators which are suitable for laboratory work.